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A use case for anon nodes - action from telecon

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Mon, 16 Jul 2001 20:23:11 +0100
Message-ID: <3B533F1F.C12AA440@hplb.hpl.hp.com>
To: rdf core <w3c-rdfcore-wg@w3.org>
I asked my colleagues if they had any use cases for anon resources
that might help us with this issue.  What follows is an (edited)
response I received.


Consider the case of describing services and being able to place adverts and
offers for such services. For example here is an (massively simplified) advert
requesting a service (all uri prefixes dropped for clarity): 

#advert123 :role "buyer"; 
           :description [:product :roses; 
                         :quantity [:units :kg; :minValue "100"]].

And here is a supplier who can offer a range of services:

#advert456 :role "seller"; 
           :description [:product :roses; 
                         :quantity [:units :kg; :maxValue "500"]]. 

Neither is a specific service. The "buyer" advert is essentially a template. The
seller is offering the existence of at least one service that matches a template
- he may have many actual instances on offer which differ by location, qos etc.

Here is an offer of specific service: 

#offer890 :inResponseTo #advert123; 
          :instanceOf   #advert456; 
          :service #service42
 
#service42 :product :roses; 
           :quantity [:units :kg; :value "200"]]; 
           :deliveryTime [:units :days; :value "2"]; 
           :deliveryMethod "TNT"; 
           etc 
           . 

Now. If we don't have anonymous nodes then we have the following problems.
 
(1) In the seller advert it would appear that the seller is only advertising a
single specific (but under-specified) service, #anon12345 or whatever, which
would be hard to distinguish from an actual service instance like #service42.
 
(2) Similarly in the buyer advert instead of describing a template, giving the
service a URI would make it appear that I am looking for a specific service with
that URI.


This is clearly similar to DanC's book buying example.

Brian
Received on Monday, 16 July 2001 15:25:40 EDT

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